I would like to see an utility that interpolates new, non-standard body parts that some
modellers (anton, phantom) have added to ameliorate the bvh file's default joint set-up.
e.g. if there's a new body part between the hip and the left/rt butt, then instead of bending
the butt 90 deg., bend the new part 45 deg. and the butt 45 deg.  similarly with the
new joint between the rcollar and the rshoulder:  if the rshoulder bends 90 deg. in a
standard default bvh file, then bend the rshoulder 45 deg. and the new intermediate
shoulder part 45 deg.